Petroleum Products
Petroleum and its products are mainly composed of carbon polymers (chains), as the backbone, with different structural and functional groups. Plastic, for example, is made of polypropylene and polybutylene which is mainly made of carbon atoms, whose monomers are linked in a chain to form polymers that make up the products.
Synthetic rubber on the other hand is made of copolymers of carbon and other addictives such as styrene. Synthetic fiber is made of nylon that is composed of a copolymer between carboxylic acid and amides.
It should be natural selection since there is no external influence implied. (like environment or genetic mutations.)
T cells
The immune response to a transplanted organ consists of both cellular (lymphocyte mediated) and humoral (antibody mediated) mechanisms. Although other cell types are also involved, the T cells are central in the rejection of grafts. The rejection reaction consists of the sensitization stage and the effector stage.
Answer:
Spirogyra is a genus of green algae that belong to the order Zygnematales. These free-flowing, filamentous algae are characterized by ribbon-shaped chloroplasts that are arranged in a helical manner inside the cells. So the name is derived from the spiral arrangement of chloroplasts in these algae.
Explanation:
